The present invention relates to a linear member feeding apparatus for feeding linear members, e.g., lead wires of tubes, one by one to a predetermined position.
In feeding linear members, such as lead wires of tubes, to a feeding chuck, the lead wires are extracted one by one from a group of lead wires stored in a case, and are delivered to the feeding chuck. Thereafter, each lead wire is fed to the stem or bulb of a tube by the feeding chuck.
Prior art lead wire feeding apparatuses are provided with a case storing a number of lead wires. One of the lead wires is nipped and fed upward by an extracting chuck. While traveling, the extracting chuck rotates as rollers thereon rotate in contact with a cam, thereby turning the lead wire held thereby to a substantially vertical position. When the extracting chuck releases its hold of the lead wire, the lead wire drops by gravity through a vertically extending fixed guide chute into a vertically extending movable guide chute. The movable guide chute is coupled to a lift rod so that it can move up and down in the vertical direction. When the lead wire drops from the fixed guide chute into the movable guide chute, the movable guide chute is moved downward by the lift rod to guide the lead wire to the feeding chuck. Receiving the lead wire, the feeding chuck feeds it to the stem of a tube.
In feeding apparatuses constructed in this manner, the movable guide chute serves to guide the lead wire between the fixed guide chute and the feeding chuck, and is designed so as to descend in accordance with the timing for the extracting chuck to release its hold of the lead wire, the time required for the natural drop of the lead wire through the fixed guide chute, and the dropping speed of the lead wire passed through the fixed guide chute.
In the prior art feeding apparatuses, however, the lead wire disengaged from the extracting chuck may touch or slide on the inner surfaces of the fixed and movable guide chutes in the course of its natural drop, and the manner of the touch or slide contact is subject to variations. Accordingly, the time for each lead wire from the extracting chuck to reach the feeding chuck varies. In contrast with this, the time of the vertical movement of the movable guide chute is fixed. Therefore, the lead wire and the movable guide chute are not synchronized in descending action; the movable guide chute may descend too fast or too slowly. As a result, the lead wire may be delivered out of time or disengaged from the feeding chuck so that it drops unexpectedly. Thus, the lead wire cannot securely be fed. The descending speed of the movable guide chute, which depends on the dropping speed of the linear wire, cannot be set freely as required and cannot therefore be made higher than the dropping speed of the linear member. Thus, it is impossible to improve the feeding efficiency.